Design And Implementation Of SIP Module And Its Security Scheme In Softswitch

As the high-speed development of internet, the Public Switched Telephone Network whose character is circuit switching is giving way to the Next-Generation Network (NGN) whose character is packet switching. NGN is based on IP networks, and its rise is a revolution in telecommunication network. The softswitch is the most important element of the NGN, it can integrate voice, data and video, and it can execute protocol translations between separate networks[3]. SIP protocol (Session Initiation Protocol) is one of the most important protocols in softswitch system. SIP is a signaling protocol developed by Internet Engineering Task Force (IETF). It is used to establish,change and tear down multimedia sessions in IP-based networks[1]. SIP is modeled upon other internet protocols such as SMTP and HTTP, It is a text-based protocol that makes it easy to realize and debug. SIP needs a number of other protocols such as SDP,UDP and TCP to provide session services. SIP is an important protocol in NGN and 3G networks, however, it needs keeping developed and consummated in future.The main contents and fruits of this paper are summarized as follows:1 It gives brief introduction about NGN and Softswitch technology.2 It gives essential introduction about SIP.3 It makes a deep discussion about the design and realization of SIP module in softswitch system, the main functions of the SIP module include SIP codec,protocol stack of SIP,the link test between softswitch,registrar,the function of FORK and load balance.4 By the deep research of security issue of SIP, this paper brings forward an improved digest authenticate scheme, and gives a solution based on the improved digest authenticate scheme in the end.